Fill break detector for a loom



Nov. 25, 1969 P. E. BLOCK 3,480,048

FILL BREAK DETECTOR FOR A LOOM Filed Feb. 12, 1968 5 Sheets-Sheet 1 l/ 9owe MWOC o l-Proms; Yw

P. E. BLOCK Nov. 25, 1969 FILL BREAK DETECTOR FOR A LOOM l/ /Oc wag @J OQTTOIQIOELYf & MVEIIQTO aul 6:.

3 Sheets-Sheet I Filed Feb. 12, 1968 Nov. 25, 1969 P. E. BLOCK FILLBREAK DETECTOR FOR A LOOM 3 Sheets-Sheet 3 Filed Feb. 12, 1968 mavaw-vm7 0w! 6. filocli,

W MM @w-rar-zmsvf United States Patent 3,480,048 FILL BREAK DETECTOR FURA LOOM Paul E. Block, South Beloit, Ill., assignor to Warner ElectricBrake & Clutch Company, South Beloit, 111., a corporation of DelawareFiled Feb. 12, 1968, Ser. No. 704,623 Int. Cl. D0311 51/18, 51/44, 51/28US. Cl. 139374 6 Claims ABSTRACT OF THE DISCLOSURE For stopping a loomin the absence of a filling thread, a fill break detector includes afeeler normally projecting into the path of a reciprocating shuttle inresting engagement with the thread last drawn from the shuttle andadapted to be retracted clear of the path by a cam before the next passof the shuttle. After each such pass, the feeler is returned to the pathand, if a correctly tensioned filling thread is not present to limit thereturn of the feeler, the latter falls to an abnormal position causingone electrical terminal on the feeler to contact a second terminal onthe cam and thereby produce an electric signal indicating the threadabsence. A circuit including the two terminals responds to the signal tostop the loom by energizing an electromagnetic brake and de-energizingan electromagnetic clutch interposed in the loom drive.

This invention relates to a fill break detector for automaticallystopping a loom upon sensing the absence of a filling thread whichnormally trails out behind a shuttle and is weaved through warp threadsas the shuttle reciprocates back and forth in a predetermined path alongan oscillating lay.

A typical fill break detector includes a feeler normally projecting intothe path of the shuttle and resting on the filling thread last drawnfrom the shuttle. Upon each pass of the shuttle along the lay, areciprocating cam retracts the feeler out of the path to clear theshuttle. Thereafter, the feeler is returned to the path to rest upon thenewly laid thread and, when the latter is present and correctlytensioned, such engagement stops movement of the feeler in a normalsensing position. If the filling thread is absent, i.e., missing orbroken, the returning feeler is not stopped in its normal sensingposition but is permitted to advance to an abnormal position beyond thesensing position. Movement of the feeler to the latter position isdetected and is utilized to initiate stoppage of the loom beforesubstantial beating of the warp threads takes place without a fillingthread or with a broken filling thread.

It is the aim of the present invention to provide a fill break detectorwhich is capable of responding much faster to movement of the feeler tothe abnormal position than existing detectors of the same general type,which is capable of stopping the loom almost instantaneously when thefeeler senses that the filling thread is absent, and which, at the sametime, may be constructed by making a simple addition to existingdetectors eliminating the need of a substantial number of partsnecessary to the operation of such existing detectors.

These and other objects and advantages of the invention will becomeapparent as the following description proceeds with reference to theaccompanying drawings, in which:

FIGURE 1 is a fragmentary perspective view schematically showing anexemplary loom equipped with a fill break detector embodying the novelfeatures of the present invention;

FIG. 2 is an enlarged fragmentary cross-section taken substantiallyalong the line 22 of FIG. 1;

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FIG. 4 is a fragmentary cross-section taken substantially along the line4-4 of FIG. 2;

FIG. 5 is a fragmentary view of parts illustrated in FIG. 4 and showingsuch parts in moved positions;

FIG. 6 is a perspective view of the fill break detector and showing thefeeler in the abnormal position;

FIG. 6a is a view similar to FIG. 5 but showing the parts in still otherpositions;

FIG. 7 is an enlarged fragmentary cross-section taken substantiallyalong the line 77 of FIG. 6;

FIG. 8 is a simplified, diagrammatic illustration of an arrangement forselectively driving and stopping the loom by means of a controlledelectromagnetic clutch and brake; and

FIG. 9 is a schematic diagram of a control circuit for selectivelyenergizing and de-energizing the windings of the clutch and brake andresponsive to movement of the feeler to the abnormal position.

While the invention has been shown and will be described in some detailwith reference to a particular embodiment thereof, there is no intentionthat it thus be limited to such detail. On the contrary, it is intendedhere to cover all modifications, alternatives and equivalents fallingwithin the spirit and scope of the invention as expressed in theappended claims.

For purposes of illustration, the invention is shown in the drawingsembodied in an automatic 100m of well known construction in which a pairof swinging picker sticks 10 (FIG. 1) are operated alternately to propela reciprocable shuttle 11 back and forth along an oscillating lay 13adapted to be advanced and retracted through forward and return strokesin timed relation with the reciprocation of the shuttle. The shuttlecarries a bobbin (not shown) of yarn, thread or other filamentarymaterial and begins one pass along the lay during each return stroke ofthe latter, one or more strands 14 (FIGS. 2 and 4) of the materialtrailing out behind and following the flight of the shuttle to fill theshed 15 (FIG. 2) of a series of warp threads 16 drawn across the lay ina conventional manner. The strand or strands 14 laid by the shuttle iscustomarily called the filling thread, which is weaved through the warpthreads as the shuttle executes its flight and then is beaten into placeduring the forward or beat-up stroke of the lay by a reed 17 (FIG. 1)located above and movable with the lay.

The picker sticks 10 and the lay 13 are pivotally mounted at 20 and 21on a suitable frame 19 (FIG. 1), and are actuated by an electric motor23 connected through gears 24, 25 to rotate a shaft 26. The latter isselectively coupled to main drive shaft 27 by engagement ordisengagement of an electromagnetic clutch CL having cooperatingelements 29 and 30 (FIG. 8) which are drivingly connected in response toenergization of a clutch winding CW. An electromagnetic brake BR isinterposed in the drive with one of its engageable elements 31 connectedto the shaft 27, and with the other such element 33 stationarilyanchored to the frame 19. When the brake elements 31 and 33 are engagedor coupled, a retarding force is exerted on the shaft 27 and the latteris stopped. The electromagnetic brake BR is actuated or de-actuated inresponse to energization or de-energization of an associated brakewinding BW.

To oscillate the lay 13, a pair of cranks 34 (FIG. 1) rotatable with themain drive shaft 27 are coupled to connecting rods 35 which in turn areattached to the lay to rock the latter about the pivots 21 in responseto rotation of the shaft. Swinging of the picker sticks 10 in timedrelation with the oscillation of the lay is effected by a shaft 36connected to the main shaft 27 via gears 37 and 39 and carrying twoangularly olfset cams 40 which alternately engage followers 41 on theends of pivoted linkages 43 coupled to the picker sticks.

In the event the shuttle 11 fails to lay a complete, correctly tensionedfilling thread 14 through the shed 15 of the warp threads 16, the driveto the loom is terminated automatically to preclude beat-up of the warpthreads without a filling thread or with a defective filling thread inthe shed. For this purpose, a fill break detector 44 (FIGS. 1 and 6) ispositioned on the lay 13 to sense the presence of the filling thread 14and, if the thread is absent (e.g. broken, missing or too looselytensioned), the detector responds to such absence and acts to initiateinterruption of the loom drive.

In mechanical construction, the preferred but exemplary fill breakdetector 44 disclosed herein is, in many respects, similar to thoseincorporated in the Model X-3 looms manufactured and sold by the DraperCorporation of Hopedale, Mass. The mechanical elements include a feeler45 formed by a series of elongated prongs projecting radially from a hub46 (FIG. 4) and disposed between the legs 47 of a center fork 49attached to the forward side of the lay 13 by screws 50 (FIG. 2). Thehub is fast on a horizontal pin 51 spanning the legs of the fork androtatably journaled therein to mount the feeler 45 for up and downswinging relative to the fork.

Normally, the feeler 45 overlies the top surface of the lay 13 and isbiased to project into the path of the shuttle 11 in resting engagementwith the filling thread 14 last drawn from the shuttle. Upon each passof the shuttle along the lay, the feeler is swung upwardly about theaxis of the pin 51 to a clear or retracted position (shown in phantom inFIG. 2) disposed out of the path of the shuttle to permit free movementof the latter. After the shuttle passes, the feeler is swung downwardlyabout the axis of the pin and is returned into the shuttle path to restupon the newly laid filling thread. With such thread present andproperly tensioned, downward swinging of the feeler is stopped in anormal sensing position shown in full in FIG. 2 by engagement of thefree end portion of the feeler with the taut thread. If, however, thethread is broken, missing or otherwise absent, the feeler continues toswing downwardly beyond the normal sensing position and advances to anabnormal position (FIG. 6) since a normal filling thread is not presentto restrain such further downward swinging. Movement of the feeler tothe abnormal position thus indicates thread absence.

The feeler 45 is retracted out of and returned to the path of theshuttle 11 as a cam 53 (FIGS. 4 and 6) moves into and out of cammingengagement with a follower which herein comprises an elongated finger orcrank 54 preferably but not necessarily attached on one end of the pin51 and projecting inwardly toward the lay 13. The cam 53 is simply ametal plate fastened to a base 55 by screws 56 and formed on its uppermargin with an upwardly opening notch 57 receiving the crank 54. Oneside wall of the notch (the right wall as viewed in FIG. 4) is inclinedupwardly to define a cam surface 59 engageable with the crank 54 to liftthe latter upwardly and thereby retract the feeler 45 as the cam ismoved to the left to a first position (FIG. Upon return of the cam tothe right to a second position (FIG. 4), the crank is free to ridedownwardly along the inclined cam surface 59 and then into the notch 57,permitting the feeler to swing downwardly under the urging of a returnspring 60 (FIGS. 2 and 4) anchored between the center fork 49 and theend of the pin 51 opposite the crank 54. The spring force biasing thefeeler is sufficient to swing the latter downwardly to its abnormalposition in the absence of the filling thread 14 but is not great enoughto cause adverse deflection of a normally tensioned thread.

Lateral movement of the cam 53 toward and away from the crank 54 (i.e.,in a direction parallel to the lengthwise dimension of the lay 13) isproduced by reciprocating a rod 61 (FIGS. 1 and 6) extending along theforward side of the lay 13 and carrying the cam base 55, the latterbeing formed with a bearing lug 63 near its lower end and being anchoredto the rod by set screws 64 (FIG. 4).

The rod is slidably mounted within a guide bracket 65 (FIG. 1) attachedto the left end portion of the lay, a bearing lug 66 (FIG. 4) formed onthe lower portion of the center fork 49, and a second guide bracket 67(FIG. 1) fastened to the right end portion of the lay. Near its leftend, the rod 61 carries a collar 69 (FIG. 3) positioned for engagementwith one arm 70 of a bell crank 71 which is pivotally mounted at 73 onthe forward side of the lay. A push rod 74 is connected at its upper endto the other arm 75 of the bell crank and is pivoted at its lower end toa pin 76 (FIG. 1) disposed forwardly of the pivot axis 21 of the lay andmounted on a second bracket 77 attached to the frame 19.

With this arrangement, oscillation of the lay 13 acts through the pushrod 74 and causes back and forth rocking of the hell crank 71 to movethe arm 70 into and out of engagement with the collar 69. As the bellcrank rocks counterclockwise about the pivot 73, the arm 70 engages thecollar to shift the rod 61 and the cam 53 to the left, (as viewed inFIG. 4), thereby causing the cam surface 59 to engage the crank 54 andlift the feeler 45 upwardly against the bias of the spring 60 and out ofthe path of the shuttle 11. When the bell crank 71 is rocked clockwise(FIG. 3), the rod 61 and the cam 53 are returned to the right by a coilspring 79 (FIG. 1) telescoped over the rod and compressed between theguide bracket 67 and a collar 80 carried on the right end portion of therod. With movement of the cam to the right, the crank 54 ridesdownwardly into the notch 57, and stops well above the bottom thereof asshown in FIG. 4 when the feeler 45 engages a tensioned filling thread 14and stops in its normal sensing position. In the absence of the fillingthread, the crank continues to move downwardly to a lower position (FIG.6a) just above the bottom of the notch as the feeler moves downwardlypast the sensing position and swings to its abnormal position.

In accordance with the primary aspect of the present invention, anelectrical signal is produced essentially at the exact instant thefeeler 45 first detects the thread absence and is created directly inresponse to movement of the feeler to the abnormal position. For thispurpose, a first electrical terminal 83 is carried by and is movablewith the feeler 45 and is normally spaced from a second terminal 84located to be contacted by the first terminal only when the feelerswings downwardly to the abnormal position. In response to suchswinging, the two terminals immediately engage one another to close acircuit and thereby produce a signal indicative of thread absence.

To simplify the construction of the detector 44, the first terminal 83is formed as part of the feeler 45 itself and, in the preferredembodiment, such terminal is constituted by the free end of the crank 54which is used in a mechanical sense to oscillate the feeler 45. Thecrank 54 is made of conductive metal and resides at ground potential byvirtue of being connected via the center fork 49 and the rod 61 to theloom frame 19. The second terminal 84 is formed physically by aconductive plate 89 (FIGS. 6 and 7) having a lower mounting portion 91attached to the outer side of the cam 53 by the same screws 56 whichfasten the cam to the base 55. Two nonconductive spacers 93 (FIG. 7) aredisposed on opposite sides of the mounting portion 91, andnon-conductive washers 94 surround the scews 56 to insulate the plate 89electrically from the cam and the screws. Electrical connection is madeto the terminal plate 89 by a wire lead 94a (FIG. 4) having an eyeletfastened to the plate by a suitable screw.

As shown in FIG. 4, the terminal 84 comprises a pointed projectionformed on an upper corner of the conductive plate 89 and positioned jutabove the bottom of the notch 57 near the lower portion of the inclinedcam surface 59. When the feeler 45 is retracted upwardly out of theshuttle path to its clear position, the first terminal 83 formed by thefree end of the crank 54 is located on the extreme upper portion of thecam surface 59 and, as

shown in FIG. 5, is spaced well above the second terminal 84 formed bythe pointed projection on the plate 89. Upon downward swinging of thefeeler, the crank 54 rides downwardly into the notch 57 but it isstopped short of contacting the pointed projection as shown in FIG. 4 solong as a normally tensioned filling thread 14 is present to stop thefeeler in its normal sensing position. However, continued downwardswinging of the feeler to the abnormal position in the absence of thefilling thread causes the crank 54 to fall deeper into the notch andinto contact with the pointed projection on the plate 89 (see FIGS. 6and 6a), thereby engaging the first and second terminals 83, 84 andcompleting an electrical circuit (to be described) in which they areconnected. The signal thus is produced by engagement of the twoterminals immediately when the feeler 45 detects the thread absence andfalls to the abnormal position. Since the terminals are held out ofcontact when the feeler is disposed in both its retracted and normalpositions, the signal is produced only when the feeler detects thethread absence and is permitted to swing to its abnormal position.

The brake BR is energized and the clutch CL is deenergized in responseto the signal produced by engagement of the terminals 83 and 84. Forthis purpose, the terminals and the clutch and brake windings CW, BW areconnected into an exemplary circuit 96 (FIG. 9) which is similar in manyrespects to that disclosed in US. patent application Ser. No. 585,577,filed Oct. 10, 1966, in the name of Roger C. Brendemuehl and assigned tothe assignee of the present application. As shown, the clutch winding CWand the brake winding BW are connected through respective siliconcontrolled rectifiers (SCRs) 95, 95' across first and second conductorsor voltage sup ply lines L1 and L2 leading from a suitable DC. voltagesource, here shown as a 30 volt battery 99. The line L1 is grounded tothe loom frame 19 and resides at a reference or ground potential, andthe line L2 is thus a 30 volt supply line. Each of the SCRs 95 and 95'is poled to conduct current through its anode-cathode path from theground line L1 to the negative line L2. The SCR 95 may be triggered intoits conductive state to excite the clutch winding CL by momentaryclosure of a start switch S1, thereby connecting a voltage dividerformed by resistors 97, 98 across the supply lines L1, L2. The gate g ofthe SCR 95 is connected to the junction between the resistors 97, 98 sothat even momentary closure of the switch S1 creates a voltage pulsemaking the gate g positive relative to the SCR cathode, and thustriggers the SCR 95 into its conductive state. As is well known, once anSCR has been triggered into conduction, it will continue to conductcurrent across its anode-cathode path even though the enabling gatesignal is removed, and until the anode-cathode potential is reduced tozero or is reversed in polarity.

Similarly, the SCR 95' may be triggered into its conductive state toexcite the brake winding BW by momentary closure of a stop switch S2 toconnect a voltage divider formed by resistors 97' and 98 between thelines L1 and L2 so that a momentary pulse is applied to the gate gmaking the latter positive with respect to its associated cathode. Tode-energize the brake BR whenever the clutch CL is energized, and viceversa, one SCR (95, 95') is always turned off when the other SCR istriggered on. For this purpose, a switching capacitor 100 is connectedbetween the anodes of the SCR 95 and the SCR 95'. As explained in moredetail in the above-identified Brendemuehl application, the capacitorturns off the SCR 95 by reversing the polarity of the voltage betweenits anode and cathode each time the SCR 95 is triggered. Similarly, thecapacitor momentarily reverses the polarity of the voltage between theanode and the cathode of the SCR 95 and causes the latter to turn offeach time the SCR 95' is triggered. In this way, the cluch CL and thebrake BW will be complementally actuated since triggering of the SCR 95(by momentary closure of the start switch S1) will initiate excitationof the clutch winding CW with simultaneous de-energization of the brakewinding BW. In a like manner, triggering of the SCR 95 (by momentaryclosure of the stop switch S2) will initiate excitation of the brakewinding BW while simultaneously de-energizing the clutch win-ding CW.

In carrying out the present invention, the signal produced by closure ofthe terminals 83, 84 in response to detection of the absence of thethread 14 is utilized to stop the loom drive. This is accomplished quitesimply and with a minimum of physical elements by connecting theterminals 83, 84 in parallel with the stop switch S2 in the circuit ofFIG. 9. The terminal 83 is at ground potential and thus connected to theline L1; and the lead 94a is simply connected to the junction betweenthe switch S2 and the resistor 97'. The terminals 83, 84 are thus in aseries circuit with resistors 97, 98' between voltage supply lines L1,L2. Thus, no current flows through the voltage divider 97, 98' in thoseinstances when both the switch S2 is open and the terminals 83, 84 areout of engagement. But when the clutch coil CW is excited and the loomis operating by drive through the engaged clutch CL, momentary contactof the detector terminals 83, 84 will produce signal current through thedivider 97', 98 from the line L1 to the line L2, thereby triggering SCRand turning SCR 95 off to disengage the clutch CL and engage the brakeBR.

With the foregoing arrangement, the loom may be conditioned foroperation by closure of a main switch S3 in the line L2 to connect thevoltage source 99. After the drive motor 23 has been started, the startswitch S1 is momentarily closed to set the SCR 95 and the SCR 95' intheir conductive and non-conductive states, respectively, and therebyenergize the clutch winding CW and de-energize the brake winding BW toallow rotation of the drive shaft 27, 36. During normal operation of theloom, the detector terminal 83 remains out of contact with the terminal84 as long as normally tensioned filling threads 14 are being drawn fromthe shuttle 11. If a filling thread should happen to be absent, thefeeler 45 immediately swings downwardly to its abnormal positionallowing the terminal 83 to fall into contact with the terminal 84 andinstantaneously trigger the SCR 95. This results in the immediateenergization of the brake winding BW and de-energization of the clutchwinding CW to stop the loom well before the lay 13 reaches the end ofits subsequent forward stroke and causes beating of the threads. Theoperator may stop the loom at any time independently of the condition ofthe terminals 83, 84 by closing the stop switch S2 and, whenever theloom is to be shut down and idle, the main switch S3 may be opened todisconnect the voltage source 99 so that neither of the windings CW orBW is excited.

From the foregoing, it will be apparent that the present inventionbrings to the art an improved fill break detector capable of stoppingthe loom immediately in response to the sensing of the absence of afilling thread and without the delays heretofore resulting from themechanical transmission of the motion of the feeler. The invention maybe readily incorporated in detectors presently being manufactured simplyby adding a conductive plate 89 to the cam 53 and by providingappropriate circuitry to the electromagnetic clutch and brake. This notonly reduces the response time of the detector but also simplifies itsoverall construction since various linkages for transmitting the motionof the feeler then may be eliminated.

I claim as my invention:

1. In a loom having an oscillating lay, a shuttle carrying a fillingthread and reciprocable back and forth on the lay along a predeterminedpath with the thread following the flight of the shuttle, a feelermounted for movement into and out of said path, means for retractingsaid feeler to a clear position out of said path while the shuttlepasses thereby and for thereafter returning said feeler into said pathto engage the thread drawn from the shuttle during such pass, saidfeeler being stopped in a normal sensing position by such thread whenthe latter is present and being permitted to advances beyond saidsensing position to an abnormal position when such thread is absent, theimprovement comprising a first electrical terminal carried by saidfeeler, a second electrical terminal mounted adjacent said feeler andspaced to be contacted by said first terminal only when said feelerreaches said abnormal position, elec trical circuit means, includingsaid first and second terminals and responsive to engagement thereof,for electrically signaling thread absence, said first terminalcomprising a cam follower carried by and movable with said feeler, saidmeans for retracting said feeler comprising a reciprocating cam movablerelative to said feeler in timed relation with the reciprocation of saidshuttle and engageable with said follower to move the feeler to saidclear position, and said second terminal being carried on said cam andbeing free of contact with said follower when said feeler is in saidsensing and clear positions while being engaged with said follower whensaid feeler is in said abnormal position.

2. In a loom having a lay, a shuttle carrying a filling thread andreciprocable back and forth on the lay along a predetermined path withthe thread trailing out behind the shuttle, a feeler mounted formovement into and out of said path and biased into the path, a cammovable to a first position to engage and retract said feeler clear ofsaid path while said shuttle passes by the feeler, said cam beingmovable to a second position to release said feeler for movement intosaid path after each pass of said shuttle to engage the thread lastdrawn from the shuttle, said feeler being stopped in a normal sensingposition by such thread when the latter is present and being permittedto advance beyond said sensing position to an abnormal position whensuch thread is absent, the improvement comprising a first electricalterminal carried by said feeler, a second electrical terminal mounted onbut insulated from said cam and located to be contacted by said firstterminal only when the feeler moves to said abnormal position and saidcam is in said second position, and electrical circuit means, includingsaid first and second terminals and responsive to engagement thereof,for electrically signaling said thread absence.

3. In a loom having an oscillating lay, a shuttle carrying a fillingthread and reciprocable back and forth on the lay along a predeterminedpath with the thread following the flight of the shuttle, a rotatablydriven shaft connected to propel said shuttle back and forth along saidlay and to oscillate the lay in timed relation, an electromagnetic brakeenergizable to exert a retarding force on said shaft, an electromagneticclutch de-energizable to interrupt the transmission of driving torque tosaid shaft, a feeler oscillating with and mounted for up and downswinging movement on said lay and biased to swing downwardly into saidpath, a follower carried by said feeler, a cam movable to a firstposition to engage said follower and swing said feeler upwardly out ofsaid path while said shuttle passes by the feeler, said cam beingmovable to a second position to release said feeler for downwardswinging into said path after each pass of said shuttle to engage thethread last drawn from the shuttle, said feeler being stopped in anormal sensing position by such thread when the latter is present andbeing permitted to swing downwardly beyond said sensing position to anabnormal position when such thread is absent, the improvementcomprising, means on said cam engageable with said follower only whensaid feeler swings downwardly to said abnormal position and operable asan incident to such engagement to produce an electrical signal, andmeans responsive to said signal for energizing said brake anddeenergizing said clutch.

4. In a loom having an oscillating lay, a shuttle carrying a fillingthread and reciprocable back and forth on the lay along a predeterminedpath with the thread following the flight of the shuttle, a rotatablydriven shaft connected to propel said shuttle back and forth along saidlay and to oscillate the lay in timed relation, an electromagnetic brakeenergizable in response to an electrical signal to exert a retardingforce on said shaft, an electromagnetic clutch de-energiza'ble inresponse to an electrical signal to interrupt the transmission ofdriving torque to said shaft, a feeler oscillating with and mounted forup and down swinging movement on said lay and biased to swing downwardlyinto said path, a follower carried by said feeler, a cam movable to afirst position to engage said follower and swing said feeler upwardly toa clear position out of said path while said shuttle passes thereby,said cam being movable to a second position to release said feeler fordownward swinging into said path after each pass of said shuttle toengage the thread last drawn from the shuttle, said feeler being stoppedin a normal sensing position by such thread when the latter is presentand being permitted to swing downwardly beyond said sensing position toan abnormal position when such thread is absent, the improvementcomprising, a normally open electrical circuit having a first terminalcarried on said cam, said circuit including a second terminal on saidfollower in spaced relation with said first terminal when said feeler isin said clear and sensing positions and movable into contact with saidfirst terminal directly in response tov swinging of said feeler to saidabnormal position, thereby to close said circuit and to produce anelectrical signal indicative of the thread absence, and means responsiveto said signal for energizing said brake and de-energizing said clutch.

5. A loom as defined in claim 4 in which said cam is formed with anupwardly inclined cam surface and in which said first terminal islocated near the lower portion of said cam surface, said follower andsaid second terminal comprising an elongated finger of conductivematerial riding on said cam surface and held above said first terminalby engagement of said feeler with said thread when the feeler is in saidsensing position, said surface being shaped to cam said finger upwardlyto swing said feeler to said clear position and being shaped to leavesaid finger free to fall downwardly into contact with said firstterminal when said feeler swings downwardly to said abnormal position inthe absence of said thread.

6. A loom as defined in claim 5 in which said circuit includes anelectrical power source having one side connected to said finger, saidfirst terminal being connected to the other side of said power sourceand being insulated electrically from said cam and said inclined camsurface.

References Cited UNITED STATES PATENTS 3,373,773 3/1968 Balentine et al.139336 FOREIGN PATENTS 1,009,546 3/1952 France. 1,140,614- 3/1957France.

830,780 7/ 1949 Germany.

HENRY S. JAUDON, Primary Examiner

